Magnesium is above iron in the activity series. It supplies electrons to the iron bar hence prevents it from rusting.
johnmulu answered the question on April 6, 2017 at 11:53
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In an experiment a certain volume of air was passed repeatedly from syringe to syringe over heated excess zinc powder as shown in the diagram below.
(Solved)
In an experiment a certain volume of air was passed repeatedly from syringe to syringe over heated excess zinc powder as shown in the diagram below.
The experiment was repeated using excess magnesium powder. In which of two experiments was the change in the volume of air greatest? Give reasons.
Date posted:
April 6, 2017
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Answers (1)
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The set-Up below was used to study some properties of air.
(Solved)
The set-Up below was used to study some properties of air.
State and explain two observations that would be made at the end of the experiment.
Date posted:
April 6, 2017
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Answers (1)
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Study the diagram below and answer the questions that follow.
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Study the diagram below and answer the questions that follow.
Write an equation for each of the two reactions that takes place in the experiment represented by the diagram
Date posted:
April 6, 2017
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Answers (1)
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a) Explain what happens to the molecules of water in the region BC in terms of Kinetic theory.
b) In what state is the water in the region DE?
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The graph below is a cooling curve for water. Study it and answer the questions that follow.
a) Explain what happens to the molecules of water in the region BC in terms of Kinetic theory.
b) In what state is the water in the region DE?
Date posted:
April 6, 2017
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Answers (1)
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The set up below was used to separate a mixture of methanol and propanol. Study it and answer the questions that follow.
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The set up below was used to separate a mixture of methanol and propanol. Study it and answer the questions that follow.
a) State the function of X.
b) Which liquid will collect first in the beaker? Given a reason.
Date posted:
April 6, 2017
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Answers (1)
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The chromatogram below was obtained from a contaminated food sample P. Contaminants Q,R,S and T are suspected to be in P. Use it to answer the following questions.
(Solved)
The chromatogram below was obtained from a contaminated food sample P. Contaminants Q,R,S and T are suspected to be in P. Use it to answer the following questions.
a) Identify the contaminant in mixture P?
b) Which is the most soluble contaminant in P?
Date posted:
April 6, 2017
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Answers (1)
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The graph below is a cooling curve of a substance from gaseous state to solid state.
(Solved)
The graph below is a cooling curve of a substance from gaseous state to solid state.
Give the name of the: a) Process taking place between to and t1
b) energy change that occurs between between t3 and t4
Date posted:
April 6, 2017
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Answers (1)
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The graph below shows a curve obtained when water at 20o was heated for 15 minutes.
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The graph below shows a curve obtained when water at 20o was heated for 15 minutes.
a) What happens to the water molecules between points W and X?
b) In which part of the curve does a change of state occur?
c) Explain why the temperature does not rise between points X and Y.
Date posted:
April 6, 2017
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Answers (1)
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A piece of chromatography paper was spotted with coloured inks obtained from pens labeled 1 to 6. The diagram below show the spots after the chromatogram was developed.
(Solved)
A piece of chromatography paper was spotted with coloured inks obtained from pens labeled 1 to 6. The diagram below show the spots after the chromatogram was developed.
a) Which two pens contained the same pigment?
b) Which pens contained only one pigment?
c) According to the chromatogram, which pigment are present in the ink of pen number 6?
Date posted:
April 5, 2017
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Answers (1)
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The set-Up below represents the apparatus that may be used to separate a mixture of two miscible liquids C and D whose boiling points are 80oC and 110oC.
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The set-Up below represents the apparatus that may be used to separate a mixture of two miscible liquids C and D whose boiling points are 80oC and 110oC.
a) Name B
b) What is the purpose of the thermometer?
c) Which liquid was collected in the test tube?
Date posted:
April 5, 2017
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Answers (1)
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The diagram below shows the relationships between the physical state of matter. Study it and answer the questions that follow.
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The diagram below shows the relationships between the physical state of matter. Study it and answer the questions that follow.
a) Identify the processes R, V, W and U.
b) Name one substance which can undergo the process represented by S and T
c) Explain whether process W is exothermic or endothermic
Date posted:
April 5, 2017
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Answers (1)
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In an experiment to separate a mixture of two organic liquids, Liquid M (b.p 56oC) and liquid N (b.p.118oC), a student set up the apparatus shown below
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In an experiment to separate a mixture of two organic liquids, Liquid M (b.p 56oC) and liquid N (b.p.118oC), a student set up the apparatus shown below
a) Identify two mistakes in the set-up.
b) What method would the student use to test the purity of the distillates obtained?
Date posted:
April 5, 2017
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Answers (1)
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The curve below represents the variation of temperature with time pure and impure samples of a solid were heated separately.
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The curve below represents the variation of temperature with time pure and impure samples of a solid were heated separately.
Which curve shows the variation in temperature for pure solid? Explain.
Date posted:
April 5, 2017
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Answers (1)
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An alkanol has the following composition by mass: Hydrogen 13.5%, oxygen 21.6% and carbon 64.9%
Determine the empirical formula of the alkanol (C = 12.0: H = 1.0; O = 16.0)
(Solved)
An alkanol has the following composition by mass: Hydrogen 13.5%, oxygen 21.6% and carbon 64.9%
Determine the empirical formula of the alkanol (C = 12.0: H = 1.0; O = 16.0)
Date posted:
February 22, 2017
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Answers (1)
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Two organic compounds P and Q decolourise acidified potassium manganate (VII) solution, but only P reacts with sodium metal to give a colourless gas.
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Two organic compounds P and Q decolourise acidified potassium manganate (VII) solution, but only P reacts with sodium metal to give a colourless gas. Which homologous series does compound P belong? Give a reason.
Date posted:
February 22, 2017
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Answers (1)
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Explain why the solubility of ethane in water is lower than of ethanol
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Explain why the solubility of ethane in water is lower than of ethanol
Date posted:
February 22, 2017
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Answers (1)
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Some animal and vegetable oils are used to make margarine and soap. Give the reagent and conditions necessary for converting the oils into:
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Some animal and vegetable oils are used to make margarine and soap. Give the reagent and conditions necessary for converting the oils into:
a) Margarine
b) Soap.
Date posted:
February 22, 2017
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Answers (1)
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Explain why the boiling point of ethanol is higher than that of hexane
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Explain why the boiling point of ethanol is higher than that of hexane (Relative molecular mass of ethanol is 46 while that of hexane is 86)
Date posted:
February 21, 2017
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Answers (1)
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The boiling point of ethanol, propanol and butanol are 78oC, 97.2oC and 117o
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The boiling point of ethanol, propanol and butanol are 78oC, 97.2oC and 117oC. Explain this trend
Date posted:
February 21, 2017
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Answers (1)
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Pentane and ethanol are miscible. Describe how water could be used to separate a mixture of pentane and ethanol
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Pentane and ethanol are miscible. Describe how water could be used to separate a mixture of pentane and ethanol
Date posted:
February 21, 2017
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Answers (1)